Movable electrode tube



April 1951 w. c. MARSHALL 2,548,385

MOVABLE ELECTRODE TUBE Filed Mar ch 11, 1946 INVENTOR. WILLIAM C.MARSHALL.

fi ATTORNEY Patented Apr. 10, 1951 UNITED STATES PATENT OFFICE 2,548,385MOVABLE ELECTRODE TUBE William C. Marshall, Oakland, Calif.

Application March 11, 1946, Serial No. 653,496

My invention relates to electronic tubes; and one of the objects of theinvention is the provision in an electronic tube in which one of theelectrodes is movable relative to another, of means by which suchmovement may be effected and controlled from outside the tube.

Another object of the invention is the provi" 8 Claims. (c1. 25o-27.5)

2 disposed in one end of the tube, and the remaining anode is pivotallymounted on an axis outside the tube to swing in an are past the fixedelectrodes so that the degree of coincidence or lapping of the anodeover the grid and cathode varies with movement of the anode about itspivotal axis. A laterally displaceable metallic bellows is interposedbetween the anode mounting and the walls of the tube so as to preservethe structural integrity of the tube while permitting lateral swingingof the anode mounting. Means external to the tube are provided formechanically moving the anode mounting to vary the arc of coincidencebetween the electrodes; and when a fixed potential is supplied tocathode and grid, the anode potential is changed in a degreecorresponding to variation in the arc of coincidence. Such outtheprovision of an electronic tube in which one of the electrodes may bemechanically moved by an outside force to vary in a corresponding degreethe electrical characteristics of the output current, so that suchvariation may be used to evaluate on a dial, or to record the degree orintensity of the moving force; and if desired, to initiatethe operationof auxiliary devices to modify or apply the moving force in strictconformity to such variations of output current.

Other objects include the provision of an electronic tube such asdescribed, characterized by low construction and installation costs, lowmaintenance cost, a high degree of accuracy in performance, and superiordependability.

The invention possesses other objects, some of which with the foregoingwill be set forth at length in the following description wherein areexplained those forms of the invention which have been selected forillustration in the draw ings accompanying and forming a part of thisspecification. In said drawings, illustrative forms of the invention areshown, but it is to be understood that it is not limited to these forms,since the invention as set forth in the claims may be embodied in aplurality of other forms.

Referring to the drawings: Figure l is an ele-.

vation of my electronic tube, parts being shown in section. Figure 2 isa detail in section, the plane of section being indicated in Figure 1 bythe line 2. Figure 3 is an elevation of a portion of my tube, partly insection, and showing a straight line arrangement of the fixedelectrodes.

In terms of broad inclusion, the tube of my invention comprises avacuumized tube enclosing three electrodes, anode, cathode and grid. Twoof these, preferably cathode and grid are fixedly put current changesare readily applied to the control and operation of indicating and/orrecording means, which evaluates the extent of anode movement in termsof the force actuating its movement, or which control other circuits.Preferably the grid and cathode assembly is so arranged that these twoelectrodes lie in an are about the axisof the anode movement. Thisarrangement gives perfect linear fidelity to the change in outputcurrent, but for many purposes, a straight line disposition of grid andcathode is sufficient; and since the straight line construction is thecheaper, it may be used where a slight departure from the linear valuesis of no consequence.

Force to move the anode mounting may be derived from an infinite varietyof machines or sources having a part which moves, or which fluctuatesvariously in response to changing conditions; and the resultingvariation in output current may be devoted to the managing of devicesfor the control of the machine or source.

Thus if the water in a reservoir is to be maintained at a constantlevel, one of my tubes is suitably;disposed in an electric circuit, anda float is mechanically connected to swing the anode back and forth inaccordance withthe rise and fall of the float.v If a constant potentialis then supplied to the tube, the changes in output current whichcorrespond exactly to the degree of anode movement, can be readilyutilized by means of well known accessory devices to indicate at adistant point the water level in the reservoir, record its changes, andautomatically manage circuits for the operation of gates in supply ordischarge lines to maintain the desired level.

In detail my electronic tube comprises an envelope conveniently made inupper part 3 and lower part 4, fused together along a line 5, after theassembly therein of the contained parts and before vacuumizing. Theupper part 3 of the tube is cylindrical and the end is formed with aflange 6 in which is embedded the flange 1, extending radially from theend B of the bellows tube 9, so that the bellows structure hermeticallycloses the adjacent end of the envelope. Fixed to the plate formin theinner end of the bellows is a stem I2 extending on both sides of theplate. The stem is pivoted by the pin E3 to the reentrant portion M ofthe bellows end 8 and is pivotally connected by pin IE to the link I!which connects the stem either directly or by intervening devices towhatever instrumentality is relied on to move it, as for example to thefloat in the case above referred to. Movement of the stem may beadjustably limited by set screws [8 incross bars [9 extending across andfixed on the end 8.

The opposite end of the stem, within the envelope terminates in a smallarcuate head to which is fixed one of the electrode elements of my tube.This may be the anode 2|, comprising a split, slightly curved tubularplate. The curve is in an arc centering at the axis of movement of thestem; and the split is opposite the head 20 and provides a freeway topermit the anode to swing freely past the leads 22, 23 and 24 for thecathode, grid and anode respectively.

These leads pass downwardly through press 25 to the terminals 26 bywhich the tube is connected in circuit in the usual way. Inside theenvelope the lead 24 is carried to the side of the envelope andconnected at 21 to the extension 28 which is connected to the metal wallof the bellows.

The grid lead 23 is extended into coils 29 forming the grid of the tube.These coils are wound about and supported by slender arcuate rods 3| and32 seating at one end in a mica end plate 33. There is but one rod 3!which seats at its inner end, adjacent the central long axis of theenvelope, in a mica plate 34. There are two similar arcuate rods 32,passing through and supporting the mid plate 34; and seating in the micaend plate 36, on the opposite side of the envelope from the plate 33.Small kinks 31, near the ends of the rods help to maintain them inposition in their supporting plates. The plates are seated against verysmall flanges 38 spun or molded in the wall of the envelope part 4, andthe supporting structure is so planned and arranged that the resilienttendency of the long supporting rod 32 to straighten out, is relied onto help hold the assembled parts in position. The cathode leads 22 areextended into a long loop 39 lying within the grid coils 29, the end 40finding support in the mica plate 33 as shown.

It will be observed that the bellows and anode may readily be assembledin the envelope part 3; and the grid and cathode assembled in theenvelope part 4, ample space and work room for the assembling beingprovided by the open ends of the envelope parts. The parts are suitablyaligned in chucks on the glass lathe, with their open ends close, butspaced apart sufficiently to permit pulling over the end of the lead 24and joining it to the projecting end of the extension 28. After thisunion 2? by tie or weld, the adjacent envelope edges are broughttogether and fused into a single envelope wall. The line of this fusingis indicated at 5 in Figure l; and is generally evidenced by a low beadsurrounding the envelope at that level. It is of course quitepracticable to run the anode lead on the outside of the envelopeconnecting its upper end to the exposed bellows end, and thus avoidingthe more delicate operation of connecting the leads through the narrowspace before final closing together of the envelope parts.

After the union of the envelope parts, the envelope is exhausted throughthe tubulation 4| in the usual way.

In assembling the bellows and anode, the parts are arranged as shown inFigure 1, with the arc of coincidence between the fixed and movableelectrodes equal to about one-half the possible total; and stresses inthe bellows equalized. If now a constant potential be supplied to theoathode and grid, any movement of the anode results in a correspondingand exactly proportional change in the output current, an increase ifthe swing of the anode is to the left so as to increase the arc ofcoincidence, and a decrease if the anode swings to the right to lessenthe arc of coincidence. Dotted lines in Figure 1 suggest the extremes ofright and left movements of the anode. The output current may beutilized through the conventional relays or in connection with otherconventional electronic tubes for the control and management of a powercircuit supplying a motor.

In Figure 3, I have shown a tube in which the structure is the same andthe anode swings over the grid-cathode assembly in the same way as inFigure 1; except that the grid and cathode are disposed in a straightline instead of in an arc. The straight unit is both simpler and cheaperto make and assembl and for most purposes the very small deviation inoutput current, due to changing separation distance between theelectrodes, is negligible. Since the only difierence between th parts ofFigures 1 and 2 is the small difference in shape of the grid-cathodeassembly, the same reference numerals are used in both figures.

I claim:

1. An electron discharge device comprising a vacuumized tub one end ofwhich is enlarged in an annular bulge to provide inside the tube anannular recess, a pair of end plates disposed diametrically in saidrecess, a pair of spaced rods carried by said plates in a generallydiametral position with respect to said annular bulge, a mid platemounted on the rods between their ends, a third rod carried by the midplate and an end plate and triangularly spaced from the other two rods,and a grid electrode coiled about the spaced three rods.

2. An electron discharge device comprising a vacuumized tube one end ofwhich is enlarged in an annular bulge to provide inside the tube anannular recess, a pair of end plates disposed diametrically in saidrecess, a pair of spaced rods carried by said plates in a generallydiametral position with respect to said annular bulge, a mid platmounted on the rods between their ends, a third rod carried by the midlate and an end plate and triangularly spaced from the other two rods, agrid electrode coiled about the spaced three rods, a cathode electrodesupported within the grid coils on the mid plate and end plate, and ananode mounted for movement in the tube and relative to the grid andcathode.

3. An electron discharge device comprising a vacuumized tube, anelectrode fixedly mounted within the tube, and a movable electrodemounted for movement in an are adjacent the fixed electrod and about afixed center of the arc outside the tube.

4. An electron discharge device comprising a vacuumized tube, anelectrode fixedly mounted within the tube, a movable electrode mountedin close overlapping relation to the fixed electrode and for pivotalmovement about a fixed axis external to the tube, and means for rockingthe movable electrode.

5. An electron discharge device comprising a vacuumized tube, anelectrode fixedly mounted within the tube, a stem mounted for pivotalmovement about a fixed axis external to the tube, a second electrodecarried by the stem inside the tube and in close overlapping relation tothe fixed electrode, and means outside the tube for rocking the stem tovary the degree of overlapping between the electrodes.

6. An electron discharge device comprising a vacuumized tube, cathodeand anode electrodes arranged within the tube in overlapping relation,means in the tube fixedly mounting one of the electrodes, and meansexternal to the tube for mounting the other electrode for movement abouta fixed axis to vary the amount of overlapping.

'7. An electron discharge device comprising a vacuumized tube, cathodeand anode and grid electrodes arranged within the tube, two of saidelectrodes being fixedly mounted and the other electrode being mountedin overlapping relation external to the tube, and mechanical means formoving said other electrode about said axis.

to th fixed electrodes and for movement to vary the amount ofoverlapping about a fixed axis 8. An electron discharge devicecomprising a vacuumized tube, a bellows including a movable end wallconstituting a portion of the vacuumized tube, a stem fixed to andextending through the wall, means outside the tube for mounting the stemfor pivotal movement about a fixed axis, cathode and anode electrodesarranged within the tube in overlapping relation, means for fixedlymounting on of said electrodes, the other electrode being mounted uponthe inner end of said stem, and means for moving the outer end of saidstem to rock'the stem about its axis to vary the amount of overlappingof said electrodes.

WILLIAM C. MARSHALL.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,831,977 Sukumlyn Nov. 17, 19312,165,981 Sampson July 11, 1939 2,167,519 Manthorne July 25, 19392,187,591 Manthorne Jan. 16, 1940 2,406,982 Zworykin et a1 Sept. 3,1946; 2,439,942 Marshall Apr. 20, 1948

